• The Korean Journal of Malacology
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• v.27 no.3
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• pp.167-173
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• 2011

This study was performed to describe the effect of water temperature, salinity and density on the eggs development of the hard clam, Meretrix petechialis. Eggs of Meretrix petechialis were turned out to be demersal isolated eggs of $82.3-86.1{\mu}m$ in an average diameter after spawning. The hatching rate of D-shaped larvae by elapsed time after spawning was the highest in fertilization immediately after spawning and distinguished decrease from 1 hour of spawning. The optimum water temperature for development of D-shaped larvae from fertilization was ranged between $25^{\circ}C$ to $27^{\circ}C$. However, D-shaped larvae was not developed at $33^{\circ}C$ of water temperature. The required time from fertilization to D-shaped larvae were 37.3 hours in $20^{\circ}C$, 20.8 hours in $25^{\circ}C$, and 15.3 hours in $30^{\circ}C$. Biological minimum temperature for the egg development was estimated to be $12.4^{\circ}C$ in average. The range of salinity for the development of eggs were 20.0-37.5 psu, optimum range was estimated to be 27.5-32.5 psu.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.113-119
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• 2009

Artificial induction of maturation by heating of the hard clam, Meretrix petechiails (Lamarck) broodstock was investigated from 25 May to 30 June in 2008. We experimented maturation by keeping the breeding water temperature at 20, 25 and $30^{\circ}C$ and as the natural water temperature and found the following results. In case of the female, maturation was the quickest in the experiment group of $30^{\circ}C$ and the maturation tended to be slower as the water temperature was lower. The similar trend was displayed among the male. At experiment completion, maturation induction rate was found to be the highest at 46.0% in the experiment group of $30^{\circ}C$ followed by 35.0% in the experiment group of $15^{\circ}C$, 18.0% in the experiment group of natural water temperature and 12.0% in the experiment group of $20^{\circ}C$. During the period of the experiment, the survival rate was of 90% or more in all groups.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.2
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• pp.277-285
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• 1993

This study was performed to evaluate the role of Waters' view and panoramic view for the interpretation of mucosal cyst of the maxillary sinus and to determine the radiographic features of that according to the sites and sizes. For this study, clinically 25 cases of mucosal cyst of the maxillary sinus were used, and experimentally with two dry skulls, rubber ball of 15mm in diameter for marked radiopacity, and two jelly balls of 8 and 20㎜ in diameter for the similar radiopacity to cyst were used. The 25 cases with 25 panoramic views and 15 Waters' views were first analyzed, and secondly, the radiographic features of artificial lesions attached to the each wall of the antrum on Waters' view and panoramic view were analyzed. The obtained results were as follows: At clinical analysis, 1. 4 cases of 13-14㎜, 4 cases of 15-19mm, 14 cases of 20-25㎜, 3 cases of over 30㎜ in dia- meter were found on panoramic views. And 24 cases of 25 cases showed no relationship with teeth, and only 1 case was associated with advanced periodontal disease 2. The majority of mucosal cysts appeared to arise the posterior portion of the floor of the sinus and were superimposed with the inominate line of zygoma and the horizontally linear image of hard palate on panoramic view. 3. Only 2 cases of 15 cases were identified on both films. At experimental analysis, 4. On Waters' view, the images of the artificial lesion of the anterior portion and midportion of the floor of the sinus were lessend in diameter compared with the real size. On panoramic views, the images of the lesion were more radiolucent with lessened diameter than images on Water' view. 5. The images of the lesion of the posterior wall and the posterior portion of the floor of sinus on panoramic view were well detected by the preeducated group but not or poorly detected by the non-preeducated observer group. 6. On Waters' view, both observer groups recognized that the cystic images of the posterior portion of the floor of the maxillary sinus were superimposed with the petrous portion of the skull.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.5
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• pp.19-27
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• 2016

This study is to find appropriate plant for infiltration swale (which is natural LID infrastructure) and suggest basic research database for building infrastructure of LID facilities. Through the research inside, it first selects the plant strong to flooding and salt tolerance. Also, the research built infiltration swale along the road, planted those strong plants and monitored how well those plants adapted into the environment. Particularly, it showered 72mm/hr-speed artificial shower, also with natural shower, given that plants were vulnerable to flood because of influx of the rain. As a result of field applicability monitoring, Pennisetum alopecuroides and Equisetum hyemale (which degrade the pollutant well and adapt into rainy environment) are planting individually, or Juncus effusus var. decipiens, Liriope platyphylla, Miscanthus sinensis Andersson, Euonymus japonica (which are strong to rainy environment) and Pennisetum alopecuroides and Equisetum hyemale are mixed planting. The research should have monitored the plant for more than one year to study them, but the research only lasted five months. Therefore, it is hard to generalize. After all, through the long term research, it should pursue study more on appropriate plant materials and database that can be the reference for infrastructure establishment and maintenance.

• Korean System Dynamics Review
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• v.15 no.3
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• pp.61-79
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• 2014

This paper deals with system thinking in the resilience of the SES (Social-Ecological Systems) around Mt. Gariwang, located in Jeongseon County, Gangwon Province, in particular with the disturbance that a new ski slope is planned to be built for the PyeongChang 2018 Winter Olympic. It first performs a literature survey and newspaper article search to summarize the controversy with regards to credible environmental and socio-economical impacts of the plan, and then elaborates a series of CLDs (Causal Loop Diagrams) to infer the dynamics of the impacts. The results imply that the natural restoration seems to be hard because the development activities can cause a great deal of damage to the ecosystem mainly due to soil degradation and the mitigation of icy valley effects with water exploitation for making artificial snow and so on. Moreover most of the households near the planned site seem to leave with land compensation, thus more policy efforts are needed to enhance the resilience of the ecosystem and the nearby society based on ecotourism.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.85-92
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• 2002

When the United Nation classified as Korea is the one of the water deficit country. The consensus was made that the water is the one of the precious national resources. Government increases their R/D budget trying to get more clean water bodies. For instances, 'Sustainable Water Resources Development' project is the one of major title in '21 Century Frontier Research project and there are several small research projects are undergoing by the Ministry of Agriculture and KARICO. However, when the environmental preservation issue has been get more emphasis, construction of the Surface Dam met the blockage from the environmentalists due to the problem of the their water buried area. Since the most fitting site for surface dam had been used in the past, some engineer move their focus on modification of the existing Dam's height to enlarge its capacity or dredging the bottom of the reservoir recently However dredging evoke water quality problem in return by accumulated materials at the bottom. Last year the Dong Gang Dam plan has been canceled by environmental problem in water buried area of the reservoir. With the point of this view, ground water gets more focus for the one of the useful alternative for clean water bodies. Underground dam technique which had widely applied once in the early nineteen eighties by the KARICO and attenuated due to engineering insufficiency. The technique is newly studied with the advanced engineering technique. Still groundwater usage rate in Korea is much lower comparing with the advanced countries and has many rooms to develop. Wells, under ground dam and radial collector wells are typical facilities up to now. There is little application in Korea for the Recharge Dam, which had been widely used in the advanced countries. The Recharge Dam is technique to conjunct surface water and groundwater body together, This technique had developed to increase groundwater recharge at the beginning This research is the result of the study on the possibility of the development of the new technology, Groundwater Reservoir' which was modified from Recharge Dam. Groundwater Reservoir is like a deep artificial lakes trenched in hard rock aquifer to get groundwater. The advantage of the Groundwater Reservoir is followings 1) It can be developed at the plains area, not in the deep valley 2) Huge water body can be developed without dam 3) Small buried area comparing surface water dam makes the least environmental effect. 4) Trenching cost can be substitute by the income of the selling rock debris 5) Outfit of the reservoir can be modified to match with the site prospect 6) Rock debris can be used as constructing materials 7) It can be used as groundwater recharge system when the heavy rains comes 8) The reservoir looks like scenery lake with huge clean water bodies.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.107-118
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• 2006

Among a variety of influencing components, time-variant seepage and long-term underground motion are important to understand the abnormal behavior of tunnels. Excessiveness of these two components could be the direct cause of severe damage on tunnels, however, it is not easy to quantify the effect of these on the behavior of tunnels. These parameters can be estimated by using inverse methods once the appropriate relationship between inputs and results is clarified. Various inverse methods or parameter estimation techniques such as artificial neural network and least square method can be used depending on the characteristics of given problems. Numerical analyses, experiments, or monitoring results are frequently used to prepare a set of inputs and results to establish the back analysis models. In this study, a back analysis method has been developed to estimate geotechnically hard-to-known parameters such as permeability of tunnel filter, underground water table, long-term rock mass load, size of damaged zone associated with seepage and long-term underground motion. The artificial neural network technique is adopted and the numerical models developed in the first part are used to prepare a set of data for learning process. Tunnel behavior, especially the displacements of the lining, has been exclusively investigated for the back analysis.

• Spatial Information Research
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• v.14 no.3 s.38
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• pp.285-297
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• 2006

We aim to investigate the morphological and environmental characteristics of royal tombs of Chosun Dynasty by using GIS technique and remotely-sensed data. Most of the royal tombs are located on the banded gneiss and granite and over the south- and east. facing slopes and have altitudinal ranges of 150 to 200 meters. Due to the time gaps, exact locational preferences of the royal families can not be understood at this moment and also proximity to the running water is hard to be quantified. Close examination of Gwangneung indicates that the artificial modification and weathering have severe impacts on the slope and stone artefacts. The results from this research can be useful to preserve the valueless cultural heritages.

• Ecology and Resilient Infrastructure
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• v.1 no.2
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• pp.82-93
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• 2014

In recent years, "ecological river restoration" taking into account the flood control, water utilization and environmental aspects of rivers is actively being investigated. However, it is hard to understand the inhabitation conditions of living organisms that live on the river with distinct characteristics have been fully reflected, and with the use of limited methods, it ends in uniformed composition of artificial rivers and a mere customary stream channel maintenance, resulting in frequently disturbed stream channel habitats As a fundamental study for investigating the habitats of living organisms that live on rivers, this study intends to examine each habitat type by dividing domestic rivers into sand rivers and gravel rivers depending on the nature of rivers and dividing sections of each river into central river sections and natural river sections. As a result, more diverse habitat types of organisms were found in the gravel rivers rather than in the sand rivers, and the habitat types of organisms in the central river sections where the river restoration project have been already conducted reached approximately 56.3 % of those that appeared in the natural river sections.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.365-373
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• 2007

Destruction of oral soft and hard tissues and resulting problems seriously affect the life quality of xerostomic patients. Although artificial saliva is the only regimen for xerostomic patients with totally abolished salivary glands, currently available artificial salivas give restricted satisfaction to patients. The purpose of this study was to contribute to the development of ideal artificial saliva through comparing viscosity and wettability between CMC solutions and human saliva. Commercially-available CMC is dissolved in simulated salivary buffer (SSB) and distilled deionized water (DDW). Various properties of human whole saliva, human glandular saliva, and a CMC-based saliva substitutes known as Salivart and Moi-Stir were compared with those of CMC solutions. Viscosity was measured with a cone-and-plate digital viscometer at six different shear rates, while wettability on acrylic resin and Co-Cr alloy was determined by the contact angle. The obtained results were as follows: 1. The viscosity of CMC solutions was proportional to CMC concentration, with 0.5% CMC solution displaying similar viscosity to stimulated whole saliva. Where as a decrease in contact angle was found with increasing CMC concentration. 2. The viscosity of human saliva was found to be inversely proportional to shear rate, a non-Newtonian (pseudoplastic) trait of biological fluids. The mean viscosity values at various shear rates increased as follows: stimulated parotid saliva, stimulated whole saliva, unstimulated whole saliva, stimulated submandibular-sublingual saliva. 3. Contact angles of human saliva on the tested solid phases were inversely correlated with viscosity, namely decreasing in the order stimulated parotid saliva, stimulated whole saliva, unstimulated whole saliva, stimulated submandibular-sublingual saliva. 4. Boiled CMC dissolved in SSB (CMC-SSB) had a lower viscosity than CMC-SSB (P < 0.01 at shear rate of $90s^{-1}$). 5. For human saliva, contact angles on acrylic resin were significantly lower than those on Co-Cr alloy (P < 0.01). 6. Comparing CMC solutions with human saliva, the contact angles between acrylic resin and human saliva solutions were significantly lower than those between acrylic resin and CMC solutions, including Salivart and Moi-Stir (P <0.01). The effectiveness of CMC solutions in terms of their rheological properties was objectively confirmed, indicating a vital role for CMC in the development of effective salivary substitutes.